Add changelog for java/v1.0.4

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

CHANGELOG.md

@@ -5,6 +5,62 @@ All notable changes to the Copilot SDK are documented in this file.
 This changelog is automatically generated by an AI agent when stable releases are published.
 See [GitHub Releases](https://github.com/github/copilot-sdk/releases) for the full list.
 
+## [java/v1.0.4](https://github.com/github/copilot-sdk/releases/tag/java/v1.0.4) (2026-06-25)
+
+### Feature: HTTP request callback support
+
+Register a `CopilotRequestHandler` on the client to intercept every outbound LLM inference HTTP or WebSocket request — for both BYOK and CAPI — and mutate, replace, or fully forward it. Useful for logging, header injection, model substitution, or custom routing. ([#1689](https://github.com/github/copilot-sdk/pull/1689), [#1775](https://github.com/github/copilot-sdk/pull/1775), [#1784](https://github.com/github/copilot-sdk/pull/1784))
+
+```java
+final class MyHandler extends CopilotRequestHandler {
+    @Override
+    protected HttpResponse<InputStream> sendRequest(HttpRequest request, CopilotRequestContext ctx) throws Exception {
+        HttpRequest mutated = HttpRequest.newBuilder(request, (n, v) -> true)
+                .header("X-Debug-Session", ctx.sessionId() == null ? "none" : ctx.sessionId())
+                .build();
+        return super.sendRequest(mutated, ctx);
+    }
+}
+
+CopilotClient client = new CopilotClient(
+    new CopilotClientOptions().setRequestHandler(new MyHandler()));
+```
+
+### Feature: `getBearerToken` callback for BYOK providers (Managed Identity)
+
+BYOK provider configs now accept a `getBearerToken` callback so the SDK consumer can resolve bearer tokens (e.g. Azure Managed Identity) on demand. The SDK takes zero Azure SDK dependency — the consumer supplies the callback using any identity library. ([#1748](https://github.com/github/copilot-sdk/pull/1748))
+
+```java
+var provider = new ProviderConfig()
+    .setType("openai")
+    .setBaseUrl(baseUrl)
+    .setGetBearerToken(args -> cred.getToken(ctx).map(AccessToken::getToken).toFuture());
+```
+
+### Feature: experimental multi-provider BYOK registry
+
+Register multiple named providers and models on a single session via `NamedProviderConfig` and `ProviderModelConfig`. Custom agents can reference provider-qualified model IDs such as `"alpha/sonnet"`. This feature is experimental. ([#1718](https://github.com/github/copilot-sdk/pull/1718))
+
+### Feature: `preamble` system message section and `preserve` action
+
+Two new customization options for system message sections. `SystemMessageSections.PREAMBLE` targets only the identity preamble without affecting its sibling sub-sections (`identity` and `tool_instructions` are now documented as section groups). The new `preserve` action protects an individually-addressable section from a group-level `remove`. ([#1713](https://github.com/github/copilot-sdk/pull/1713))
+
+### Other changes
+
+- feature: add optional `memory` configuration (`MemoryConfiguration`) to session create and resume ([#1617](https://github.com/github/copilot-sdk/pull/1617))
+- feature: `defer` parameter on tool definitions controls eager vs. lazy tool loading (`"auto"` or `"never"`) ([#1632](https://github.com/github/copilot-sdk/pull/1632))
+- feature: `otlpProtocol` telemetry option for configuring OTLP export transport (`"http/json"` or `"http/protobuf"`) ([#1648](https://github.com/github/copilot-sdk/pull/1648))
+- feature: `ModelBilling.tokenPrices` surfaced on public SDK types, exposing per-tier pricing and context window limits ([#1633](https://github.com/github/copilot-sdk/pull/1633))
+- feature: `CapiSessionOptions.enableWebSocketResponses` and `ProviderConfig.transport` for WebSocket transport control on session create/resume ([#1711](https://github.com/github/copilot-sdk/pull/1711))
+- improvement: call `runtime.shutdown` during client stop for deterministic OTEL telemetry flush before process cleanup ([#1667](https://github.com/github/copilot-sdk/pull/1667))
+- improvement: rename `SystemPromptSections` → `SystemMessageSections` for cross-SDK consistency; old class deprecated with `forRemoval=true` ([#1683](https://github.com/github/copilot-sdk/pull/1683))
+
+### New contributors
+
+- @almaleksia made their first contribution in [#1632](https://github.com/github/copilot-sdk/pull/1632)
+- @dereklegenzoff made their first contribution in [#1711](https://github.com/github/copilot-sdk/pull/1711)
+- @ellismg made their first contribution in [#1750](https://github.com/github/copilot-sdk/pull/1750)
+
 ## [v1.0.2](https://github.com/github/copilot-sdk/releases/tag/v1.0.2) (2026-06-18)
 
 ### Feature: opt-in memory for sessions